[Grammar] It can't have been him / It couldn't have been him

[englishhobby]

Which modal verb should be used In the following situation:

I saw Jim in town yeserday. - It couldn't have been / can't have been him. He is away on business, that's for sure.

What's the difference between couldn't have been and can't have been - they are both used to refer to some past event, so can I use any of them in the above context?
:?:

 

[Rover_KE]

You can use either of them in the above context.

(We only say any of them when there are more than two alternatives.)

Rover

 

[englishhobby]

There is no significant difference in meaning, isn't there?